In many applications in the body involving implants, it is often desirable to create some type of connection between a tissue (a tissue is defined as any part of the body) and the implant (an implant is herein defined as anything which could be implanted into the body, e.g. a breast implant, a intraocular lens or a drug delivery device). The most common way to create such a connection is to use some type of adhesive. The adhesives used in general are cyanoacrylates and fibrin glues. Cyanoacrylates (disclosed in e.g. U.S. Pat. No. 6,183,593 and EP 0925795) have the advantage of fast bonding speed and strong bonds. However, they are also known to be toxic to some tissues and their potential degradation products are suspected to be carcinogenic. Further, the strong bonds formed can be a disadvantage in applications where flexible bonds are required. The fibrin glues (disclosed in e.g. U.S. Pat. No. 6,699,484 and U.S. Pat. No. 6,596,318) have the advantage of being degradable and non-toxic. However, the disadvantage with using fibrin glue is that tissue binding with fibrin glue cannot be subjected to even moderate tensile strength without rupturing the bond. Further, there is a risk of viral infection since fibrin glue is often of animal origin.
Another type of adhesive composition is provided by WO 02/087642, in which a water-absorbent two-phase adhesive composition containing a hydrophobic phase and a hydrophilic phase is disclosed. The hydrophobic phase is composed of a crosslinked hydrophobic polymer composition and the hydrophilic phase is a water-absorbent blend of a hydrophilic polymer and a complementary oligomer capable of crosslinking the hydrophilic polymer through hydrogen bonding, ionic bonding, and/or covalent bonding. The composition is useful as a bioadhesive, for affixing drug delivery systems, wound dressings, bandages, cushions, or the like to a body surface such as skin or mucosal tissue.
International Patent Application WO 03/097759 discloses biomedical adhesives comprising multi-functionally activated groups. The adhesives are used for bonding an implant to a surface, which surface can be either electrophilic or nucleophilic as long as it is opposite to the functional groups of the adhesive. The adhesive is coated on the implant.
There is, however, still a need for a biocompatible composition comprising compounds that will easily provide a coating on the tissue surface, which will facilitate the connection between said surface and an implant, and that will create a safe and flexible connection between said surface and the implant.
Cataract extraction is among the most commonly performed operations in the world. In this operation the natural lens is removed and replaced with an artificial intraocular lens (IOL), which will mimic the transparency and the refractive function of a natural lens. The intraocular lens can either be implanted into the capsular bag or injected as an ophthalmic composition into the capsular bag and then crosslinked (the capsular bag is used as a mold). The removal of the natural lens can be performed by several known techniques, e.g. phacoemulsification, which technique entails the application of ultrasonic energy or other forms of energy to the natural lens, thus breaking the lens into fragments that can be aspirated from the capsular bag.
Lens removal with an artificial lens implantation provides significant benefits to most cataract patients (currently lens removal with artificial lens implantation is increasingly carried out in a non-catarcatous eye, so-called refractive lens exchange, often with the purpose to relieve presbyopia). However, it is estimated that up to fifty percent of all patients, who have implants placed within the capsular bag, will develop capsular opacification (CO), also known as secondary cataract or “after cataract”, within five years after surgery. CO is an opacification located on the inner surface of capsular bag, whether located posteriorly (PCO) or anteriorly (ACO) and is caused by deposition (the cell may be deposited on the interior surface of the capsular bag or on the implanted lens) or ingrowths of cells, cell derivatives and/or fibers into the visual axis and/or extracellular matrix production by the lens epithelial cells. The problem with CO is that the optical axis of the eye will be occluded, which will cloud the vision. Ophthalmic surgeons take considerable care in trying to remove as many as possible of the lens epithelial cells prior to implantation or injection of an artificial lens. However, despite these efforts, a significant number of lens epithelial cells are usually left on the interior surface of the capsular bag since these cells are difficult to view and often difficult to reach and virtually impossible to completely remove.
The most common treatment for postoperative PCO uses laser energy, however, the laser energy applied to the posterior membrane of the capsular bag is ordinarily directed though the implant and might damage the optic of said implant. Accordingly, it is desirable to prevent the occurrence of CO rather than treating CO. Various procedures for the prevention of CO have been suggested in recent years and a lot of those procedures have included the application of chemicals into of the capsular bag in order to destroy residual lens epithelial cells, e.g. WO 02/47728 that discloses a treatment of posterior capsular opacification by using a product comprising death receptor ligand covalently bound to a polymer. However, few if any of these procedures have proven to be particularly successful in the prevention of CO due to the fact that it is extremely difficult to destroy residual lens epithelial cells without simultaneously destroying other cells within the eye.
Another method for preventing secondary cataract is disclosed in the granted U.S. Pat. No. 6,702,853. This granted patent discloses a system and a method for preventing capsular opacification by applying an adhesive to at least one surface of implanted lens.
Thus, there is still a need for a method for preventing secondary cataract for system using injectable lenses, which method will affect the tissues and the optical properties of the injectable lens as little as possible.